The present invention relates to cold-atom chips and, more particularly, to vacuum cells for sensing and manipulating cold atoms. A major objective of the invention is to provide an improved cold-atom vacuum cell.
Cold atoms and ions are on the way from the research lab to technical applications such as 1) atom interferometry, e.g., used for ultra sensitive sensors (M. A. Kasevich. Coherence with Atoms. Science, 298, 1363 (2002)); 2) time and frequency standards; and 3) quantum information processing. All current cold atom and ion applications require an ultrahigh vacuum (UHV) apparatus with optical access. In addition, a multipolar electrical feedthrough is typically required when cold atoms are produced and manipulated with atom chips (J. Reichel, W. Hansel, and T. W. Hansch. Atomic Micromanipulation with Magnetic Surface Traps. Phys. Rev. Lett., 83, 3398 (1999); R. Folman, P. Krüger, D. Cassettari, B. Hessmo, T. Maier, and J. Schmiedmayer. Controlling Cold Atoms using Nanofabricated Surfaces: Atom Chips, Phys. Rev. Lett., 84, 4749 (2000); R. Folman, P. Krüger, J. Schmiedmayer, J. Denschlag, and C. Henkel. Microscopic atom optics: From wires to an atom chip. Adv. At. Mol. Phys., 48, 263 (2002); and J. Reichel. Microchip traps and Bose-Einstein condensation. Appl. Phys. B, 74, 469 (2002). More specifically, the vacuum chamber of an atom chip typically provides: 1) an ultrahigh vacuum (base pressure 10−7 Pa or below at the atom-chip surface; 2) multi-line electrical connections between the microchip and the outside; and 3) optical access (windows) for laser cooling, typically, at least 1 cm2 optical access from several directions.
Today's implementations typically have 10–30 electrical contacts. The typical number of contacts is expected to rise in the future, as it did for microprocessors, increasing the electrical feedthrough requirements. Standard atom chip apparatuses use commercial electrical feedthroughs (CF flanges), and use one of two techniques to give optical access to the chip: 1) custom-made glass cells with special seals; or 2) standard, flange-mounted viewports on a metal chamber.
All existing atom chip implementations use the microchip to create magnetic fields. In one case, electric fields have also been used (P. Krüger, X. Luo, M. W. Klein, A. Brugger, A. Haase, S. Wildermuth, S. Groth, I. Bar-Joseph, R. Folman, and J. Schmiedmayer. Trapping and Manipulating Neutral Atoms with Electrostatic Fields. Phys. Rev. Lett., 91, 233201 (2003).) All references cited herein are incorporated by reference herein in their entirety.
Optical atom chips (with integrated optics on the chip) have been proposed, e.g., by G. Birkl, F. B. J. Buchkremer, R. Dumke, and W. Ertmer. Atom optics with microfabricated optical elements. Optics Comm., 191, 67 (2001) but not realized. The state of the art has been reviewed extensively by R. Folman, P. Krüger, J. Schmiedmayer, J. Denschlag, and C. Henkel. Microscopic atom optics: From wires to an atom chip, Adv. Opt. Mol. Phys. Academic Press, Boston (2002), while magnetic atom chips have been reviewed by J. Reichel, ibid. No commercial atom chip products exist as yet. What is needed is an improved cold-atom cell with good vacuum characteristics as well as sufficient optical and electrical access. Preferably, such a cell would be compact for portable applications.